I do have preconceived ideas. My idea is that I am human and I can recognize other humans. Are Aborigines human?
In the collection of fossils in post #405, most scientists place the dividing line between C and D. That is some 2 million years ago.
Based on this, you should be able to infer that Aborigines are human.
Yes, of course they are. Darwin himself concluded this in "The Descent of Man". You need to read my explanations again. The nature of your questions and remarks implies that you haven't understood my posts on this subject. I tried to put together a clarification, but I found myself just using the same form of words again. If all you want to do is recognise humans now, then a morphological or DNA test will suffice, and science can do this. (This is because humans are not a "Ring Species". If humans were a ring species then it is much harder to define what it is to be a member of that species.) But going backwards in time and pointing to "the first human" and "the last non-human" in our ancestors would not be meaningfuly and objectively possible. If you think that this means you've scored some kind of clever victory over "those stupid scientists who can't even define human" then I wish you joy of your victory.
I thought about this some more.
Imagine that "The Designer" makes specially for you 10,000 creatures standing in a line, and that those creatures form a sequence from ape to human, each changing by 1/10,000 of the difference between ape and human. Presumably you wouldn't just say that only the very last creature in the line was human? Now, you say you can recognise "other humans". Do you think that you would be able to confidently point at one particular creature in that sequence and say "that is the first human", and "The one to its left is the last ape". If someone disagreed with you about where the dividing line lay on what basis would you argue with them?